#region License
/*---------------------------------------------------------------------------------*\

	Distributed under the terms of an MIT-style license:

	The MIT License

	Copyright (c) 2006-2008 Stephen M. McKamey

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE.

\*---------------------------------------------------------------------------------*/
#endregion License

using System;
using System.IO;
using System.ComponentModel;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Xml;

namespace JsonFx.Internal
{
  /// <summary>
  /// Writer for producing JSON data.
  /// </summary>
  public class JsonWriter : IDisposable
  {
    #region Constants

    public const string JsonMimeType = "application/json";

    internal const string TypeGenericIDictionary = "System.Collections.Generic.IDictionary`2";

    private const string TypeBoolean = "System.Boolean";
    private const string TypeChar = "System.Char";
    private const string TypeByte = "System.Byte";
    private const string TypeInt16 = "System.Int16";
    private const string TypeInt32 = "System.Int32";
    private const string TypeInt64 = "System.Int64";
    private const string TypeSByte = "System.SByte";
    private const string TypeUInt16 = "System.UInt16";
    private const string TypeUInt32 = "System.UInt32";
    private const string TypeUInt64 = "System.UInt64";
    private const string TypeSingle = "System.Single";
    private const string TypeDouble = "System.Double";
    private const string TypeDecimal = "System.Decimal";

    private const string ErrorGenericIDictionary = "Types which implement Generic IDictionary<TKey, TValue> also need to implement IDictionary to be serialized.";

    #endregion Constants

    #region Fields

    private readonly TextWriter writer = null;
    private string typeHintName = null;
    private bool strictConformance = true;

    private bool prettyPrint = false;
    private bool useXmlSerializationAttributes = false;
    private int depth = 0;
    private string tab = "\t";

    #endregion Fields

    #region Init

    /// <summary>
    /// Ctor.
    /// </summary>
    /// <param name="output">TextWriter for writing</param>
    public JsonWriter(TextWriter output)
    {
      this.writer = output;
    }

    /// <summary>
    /// Ctor.
    /// </summary>
    /// <param name="output">Stream for writing</param>
    public JsonWriter(Stream output)
    {
      this.writer = new StreamWriter(output, Encoding.UTF8);
    }

    /// <summary>
    /// Ctor.
    /// </summary>
    /// <param name="output">File name for writing</param>
    public JsonWriter(string outputFileName)
    {
      Stream stream = new FileStream(outputFileName, FileMode.Create, FileAccess.Write, FileShare.Read);
      this.writer = new StreamWriter(stream, Encoding.UTF8);
    }

    /// <summary>
    /// Ctor.
    /// </summary>
    /// <param name="output">StringBuilder for appending</param>
    public JsonWriter(StringBuilder output)
    {
      this.writer = new StringWriter(output, System.Globalization.CultureInfo.InvariantCulture);
    }

    #endregion Init

    #region Properties

    /// <summary>
    /// Gets and sets the property name used for type hinting.
    /// </summary>
    public string TypeHintName
    {
      get { return this.typeHintName; }
      set { this.typeHintName = value; }
    }

    /// <summary>
    /// Gets and sets if JSON will be formatted for human reading.
    /// </summary>
    public bool PrettyPrint
    {
      get { return this.prettyPrint; }
      set { this.prettyPrint = value; }
    }

    /// <summary>
    /// Gets and sets the string to use for indentation
    /// </summary>
    public string Tab
    {
      get { return tab; }
      set { tab = value; }
    }

    /// <summary>
    /// Gets and sets the lien terminator string
    /// </summary>
    public string NewLine
    {
      get { return this.writer.NewLine; }
      set { this.writer.NewLine = value; }
    }

    /// <summary>
    /// Gets and sets if should use XmlSerialization Attributes.
    /// </summary>
    /// <remarks>
    /// Respects XmlIgnoreAttribute, ...
    /// </remarks>
    public bool UseXmlSerializationAttributes
    {
      get { return this.useXmlSerializationAttributes; }
      set { this.useXmlSerializationAttributes = value; }
    }

    /// <summary>
    /// Gets and sets if should conform strictly to JSON spec.
    /// </summary>
    /// <remarks>
    /// Setting to true causes NaN, Infinity, -Infinity to serialize as null.
    /// </remarks>
    public bool StrictConformance
    {
      get { return this.strictConformance; }
      set { this.strictConformance = value; }
    }

    /// <summary>
    /// Gets the underlying TextWriter.
    /// </summary>
    public TextWriter TextWriter
    {
      get { return this.writer; }
    }

    #endregion Properties

    #region Static Methods

    /// <summary>
    /// A fast method for serializing an object to JSON
    /// </summary>
    /// <param name="value"></param>
    /// <returns></returns>
    public static string Serialize(object value)
    {
      StringBuilder output = new StringBuilder();

      using (JsonWriter writer = new JsonWriter(output))
      {
        writer.Write(value);
      }

      return output.ToString();
    }

    #endregion Static Methods

    #region Public Methods

    public virtual void Write(object value)
    {
      this.Write(value, false);
    }

    private void Write(object value, bool isProperty)
    {
      if (isProperty && this.prettyPrint)
      {
        this.writer.Write(' ');
      }

      if (value == null)
      {
        this.writer.Write(JsonReader.LiteralNull);
        return;
      }

      if (value is IJsonSerializable)
      {
        try
        {
          if (isProperty)
          {
            this.depth++;
            this.WriteLine();
          }
          ((IJsonSerializable)value).WriteJson(this);
        }
        finally
        {
          if (isProperty)
          {
            this.depth--;
          }
        }
        return;
      }

      if (value is Enum)
      {
        this.Write((Enum)value);
        return;
      }

      if (value is String)
      {
        this.Write((String)value);
        return;
      }

      // IDictionary test must happen BEFORE IEnumerable test
      // since IDictionary implements IEnumerable
      if (value is IDictionary)
      {
        try
        {
          if (isProperty)
          {
            this.depth++;
            this.WriteLine();
          }
          this.WriteObject((IDictionary)value);
        }
        finally
        {
          if (isProperty)
          {
            this.depth--;
          }
        }
        return;
      }

      Type type = value.GetType();
      if (type.GetInterface(JsonWriter.TypeGenericIDictionary) != null)
      {
        throw new JsonSerializationException(JsonWriter.ErrorGenericIDictionary);
      }

      if (value is IEnumerable)
      {
        if (value is XmlNode)
        {
          this.Write((System.Xml.XmlNode)value);
          return;
        }

        try
        {
          if (isProperty)
          {
            this.depth++;
            this.WriteLine();
          }
          this.WriteArray((IEnumerable)value);
        }
        finally
        {
          if (isProperty)
          {
            this.depth--;
          }
        }
        return;
      }

      if (value is DateTime)
      {
        this.Write((DateTime)value);
        return;
      }

      if (value is Guid)
      {
        this.Write((Guid)value);
        return;
      }

      if (value is Uri)
      {
        this.Write((Uri)value);
        return;
      }

      if (value is TimeSpan)
      {
        this.Write((TimeSpan)value);
        return;
      }

      if (value is Version)
      {
        this.Write((Version)value);
        return;
      }

      // cannot use 'is' for ValueTypes, using string comparison
      // these are ordered based on an intuitive sense of their
      // frequency of use for nominally better switch performance
      switch (type.FullName)
      {
        case JsonWriter.TypeDouble:
          {
            this.Write((Double)value);
            return;
          }
        case JsonWriter.TypeInt32:
          {
            this.Write((Int32)value);
            return;
          }
        case JsonWriter.TypeBoolean:
          {
            this.Write((Boolean)value);
            return;
          }
        case JsonWriter.TypeDecimal:
          {
            // From MSDN:
            // Conversions from Char, SByte, Int16, Int32, Int64, Byte, UInt16, UInt32, and UInt64
            // to Decimal are widening conversions that never lose information or throw exceptions.
            // Conversions from Single or Double to Decimal throw an OverflowException
            // if the result of the conversion is not representable as a Decimal.
            this.Write((Decimal)value);
            return;
          }
        case JsonWriter.TypeByte:
          {
            this.Write((Byte)value);
            return;
          }
        case JsonWriter.TypeInt16:
          {
            this.Write((Int16)value);
            return;
          }
        case JsonWriter.TypeInt64:
          {
            this.Write((Int64)value);
            return;
          }
        case JsonWriter.TypeChar:
          {
            this.Write((Char)value);
            return;
          }
        case JsonWriter.TypeSingle:
          {
            this.Write((Single)value);
            return;
          }
        case JsonWriter.TypeUInt16:
          {
            this.Write((UInt16)value);
            return;
          }
        case JsonWriter.TypeUInt32:
          {
            this.Write((UInt32)value);
            return;
          }
        case JsonWriter.TypeUInt64:
          {
            this.Write((UInt64)value);
            return;
          }
        case JsonWriter.TypeSByte:
          {
            this.Write((SByte)value);
            return;
          }
        default:
          {
            // structs and classes
            try
            {
              if (isProperty)
              {
                this.depth++;
                this.WriteLine();
              }
              this.WriteObject(value);
            }
            finally
            {
              if (isProperty)
              {
                this.depth--;
              }
            }
            return;
          }
      }
    }

    public virtual void WriteBase64(byte[] value)
    {
      this.Write(Convert.ToBase64String(value));
    }

    public virtual void Write(DateTime value)
    {
      // UTC DateTime in ISO-8601
      value = value.ToUniversalTime();
      this.Write(String.Format("{0:s}Z", value));
    }

    public virtual void Write(Guid value)
    {
      this.Write(value.ToString("D"));
    }

    public virtual void Write(Enum value)
    {
      string enumName = null;

      Type type = value.GetType();

      if (type.IsDefined(typeof(FlagsAttribute), true) && !Enum.IsDefined(type, value))
      {
        Enum[] flags = JsonWriter.GetFlagList(type, value);
        string[] flagNames = new string[flags.Length];
        for (int i = 0; i < flags.Length; i++)
        {
          flagNames[i] = JsonNameAttribute.GetJsonName(flags[i]);
          if (String.IsNullOrEmpty(flagNames[i]))
          {
            flagNames[i] = flags[i].ToString("f");
          }
        }
        enumName = String.Join(", ", flagNames);
      }
      else
      {
        enumName = JsonNameAttribute.GetJsonName(value);
        if (String.IsNullOrEmpty(enumName))
        {
          enumName = value.ToString("f");
        }
      }

      this.Write(enumName);
    }

    public virtual void Write(string value)
    {
      if (value == null)
      {
        this.writer.Write(JsonReader.LiteralNull);
        return;
      }

      int length = value.Length;
      int start = 0;

      this.writer.Write(JsonReader.OperatorStringDelim);

      for (int i = start; i < length; i++)
      {
        if (value[i] <= '\u001F' ||
          value[i] >= '\u007F' ||
          value[i] == '<' ||
          value[i] == '\t' ||
          value[i] == JsonReader.OperatorStringDelim ||
          value[i] == JsonReader.OperatorCharEscape)
        {
          this.writer.Write(value.Substring(start, i - start));
          start = i + 1;

          switch (value[i])
          {
            case JsonReader.OperatorStringDelim:
            case JsonReader.OperatorCharEscape:
              {
                this.writer.Write(JsonReader.OperatorCharEscape);
                this.writer.Write(value[i]);
                continue;
              }
            case '\b':
              {
                this.writer.Write("\\b");
                continue;
              }
            case '\f':
              {
                this.writer.Write("\\f");
                continue;
              }
            case '\n':
              {
                this.writer.Write("\\n");
                continue;
              }
            case '\r':
              {
                this.writer.Write("\\r");
                continue;
              }
            case '\t':
              {
                this.writer.Write("\\t");
                continue;
              }
            default:
              {
                this.writer.Write("\\u{0:X4}", Char.ConvertToUtf32(value, i));
                continue;
              }
          }
        }
      }

      this.writer.Write(value.Substring(start, length - start));

      this.writer.Write(JsonReader.OperatorStringDelim);
    }

    #endregion Public Methods

    #region Primative Writer Methods

    public virtual void Write(bool value)
    {
      this.writer.Write(value ? JsonReader.LiteralTrue : JsonReader.LiteralFalse);
    }

    public virtual void Write(byte value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(sbyte value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(short value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(ushort value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(int value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(uint value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(long value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(ulong value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(float value)
    {
      if (this.StrictConformance && (Single.IsNaN(value) || Single.IsInfinity(value)))
      {
        this.writer.Write(JsonReader.LiteralNull);
      }
      else
      {
        this.writer.Write("{0:r}", value);
      }
    }

    public virtual void Write(double value)
    {
      if (this.StrictConformance && (Double.IsNaN(value) || Double.IsInfinity(value)))
      {
        this.writer.Write(JsonReader.LiteralNull);
      }
      else
      {
        this.writer.Write("{0:r}", value);
      }
    }

    public virtual void Write(decimal value)
    {
      this.writer.Write("{0:g}", value);
    }

    public virtual void Write(char value)
    {
      this.Write(new String(value, 1));
    }

    public virtual void Write(TimeSpan value)
    {
      this.Write(value.Ticks);
    }

    public virtual void Write(Uri value)
    {
      this.Write(value.ToString());
    }

    public virtual void Write(Version value)
    {
      this.Write(value.ToString());
    }

    public virtual void Write(XmlNode value)
    {
      // TODO: translate XML to JSON
      this.Write(value.OuterXml);
    }

    #endregion Primative Writer Methods

    #region Writer Methods

    protected internal virtual void WriteArray(IEnumerable value)
    {
      bool appendDelim = false;

      this.writer.Write(JsonReader.OperatorArrayStart);

      this.depth++;
      try
      {
        foreach (object item in value)
        {
          if (appendDelim)
          {
            this.writer.Write(JsonReader.OperatorValueDelim);
          }
          else
          {
            appendDelim = true;
          }

          this.WriteLine();
          this.Write(item, false);
        }
      }
      finally
      {
        this.depth--;
      }

      if (appendDelim)
      {
        this.WriteLine();
      }
      this.writer.Write(JsonReader.OperatorArrayEnd);
    }

    protected virtual void WriteObject(IDictionary value)
    {
      bool appendDelim = false;

      this.writer.Write(JsonReader.OperatorObjectStart);

      this.depth++;
      try
      {
        foreach (object name in value.Keys)
        {
          if (appendDelim)
          {
            this.writer.Write(JsonReader.OperatorValueDelim);
          }
          else
          {
            appendDelim = true;
          }

          this.WriteLine();
          this.Write((String)name);
          this.writer.Write(JsonReader.OperatorNameDelim);
          this.Write(value[name], true);
        }
      }
      finally
      {
        this.depth--;
      }

      if (appendDelim)
      {
        this.WriteLine();
      }
      this.writer.Write(JsonReader.OperatorObjectEnd);
    }

    protected virtual void WriteObject(object value)
    {
      bool appendDelim = false;

      this.writer.Write(JsonReader.OperatorObjectStart);

      this.depth++;
      try
      {
        Type objType = value.GetType();

        if (!String.IsNullOrEmpty(this.TypeHintName))
        {
          if (appendDelim)
          {
            this.writer.Write(JsonReader.OperatorValueDelim);
          }
          else
          {
            appendDelim = true;
          }

          this.WriteLine();
          this.Write(this.TypeHintName);
          this.writer.Write(JsonReader.OperatorNameDelim);
          this.Write(objType.FullName, true);
        }

        // serialize public properties
        PropertyInfo[] properties = objType.GetProperties();
        foreach (PropertyInfo property in properties)
        {
          // NOTE(nedajil): I disabled checking writeability of property 
          // since it's not very convinient and leads to fake setters.
          if (/*!property.CanWrite ||*/ !property.CanRead)
          {
            continue;
          }

          if (this.IsIgnored(objType, property, value))
          {
            continue;
          }

          object propertyValue = property.GetValue(value, null);
          if (this.IsDefaultValue(property, propertyValue))
          {
            continue;
          }

          if (appendDelim)
          {
            this.writer.Write(JsonReader.OperatorValueDelim);
          }
          else
          {
            appendDelim = true;
          }

          string propertyName = JsonNameAttribute.GetJsonName(property);
          if (String.IsNullOrEmpty(propertyName))
          {
            propertyName = property.Name;
          }

          this.WriteLine();
          this.Write(propertyName);
          this.writer.Write(JsonReader.OperatorNameDelim);
          this.Write(propertyValue, true);
        }

        // serialize public fields
        FieldInfo[] fields = objType.GetFields();
        foreach (FieldInfo field in fields)
        {
          if (!field.IsPublic || field.IsStatic)
          {
            continue;
          }

          if (this.IsIgnored(objType, field, value))
          {
            continue;
          }

          object fieldValue = field.GetValue(value);
          if (this.IsDefaultValue(field, fieldValue))
          {
            continue;
          }

          if (appendDelim)
          {
            this.writer.Write(JsonReader.OperatorValueDelim);
            this.WriteLine();
          }
          else
          {
            appendDelim = true;
          }

          string fieldName = JsonNameAttribute.GetJsonName(field);
          if (String.IsNullOrEmpty(fieldName))
          {
            fieldName = field.Name;
          }

          // use Attributes here to control naming
          this.Write(fieldName);
          this.writer.Write(JsonReader.OperatorNameDelim);
          this.Write(fieldValue, true);
        }
      }
      finally
      {
        this.depth--;
      }

      if (appendDelim)
      {
        this.WriteLine();
      }
      this.writer.Write(JsonReader.OperatorObjectEnd);
    }

    protected virtual void WriteLine()
    {
      if (!this.prettyPrint)
      {
        return;
      }

      this.writer.WriteLine();
      for (int i = 0; i < this.depth; i++)
      {
        this.writer.Write(this.tab);
      }
    }

    #endregion Writer Methods

    #region Private Methods

    /// <summary>
    /// Determines if the property or field should not be serialized.
    /// </summary>
    /// <param name="objType"></param>
    /// <param name="member"></param>
    /// <param name="value"></param>
    /// <returns></returns>
    /// <remarks>
    /// Checks these in order, if any returns true then this is true:
    /// - is flagged with the JsonIgnoreAttribute property
    /// - has a JsonSpecifiedProperty which returns false
    /// </remarks>
    private bool IsIgnored(Type objType, MemberInfo member, object obj)
    {
      if (JsonIgnoreAttribute.IsJsonIgnore(member))
      {
        return true;
      }

      string specifiedProperty = JsonSpecifiedPropertyAttribute.GetJsonSpecifiedProperty(member);
      if (!String.IsNullOrEmpty(specifiedProperty))
      {
        PropertyInfo specProp = objType.GetProperty(specifiedProperty);
        if (specProp != null)
        {
          object isSpecified = specProp.GetValue(obj, null);
          if (isSpecified is Boolean && !Convert.ToBoolean(isSpecified))
          {
            return true;
          }
        }
      }

      if (this.UseXmlSerializationAttributes)
      {
        if (JsonIgnoreAttribute.IsXmlIgnore(member))
        {
          return true;
        }

        PropertyInfo specProp = objType.GetProperty(member.Name + "Specified");
        if (specProp != null)
        {
          object isSpecified = specProp.GetValue(obj, null);
          if (isSpecified is Boolean && !Convert.ToBoolean(isSpecified))
          {
            return true;
          }
        }
      }

      return false;
    }

    /// <summary>
    /// Determines if the member value matches the DefaultValue attribute
    /// </summary>
    /// <returns>if has a value equivalent to the DefaultValueAttribute</returns>
    private bool IsDefaultValue(MemberInfo member, object value)
    {
      DefaultValueAttribute attribute = Attribute.GetCustomAttribute(member, typeof(DefaultValueAttribute)) as DefaultValueAttribute;
      if (attribute == null)
      {
        return false;
      }

      if (attribute.Value == null)
      {
        return (value == null);
      }

      return (attribute.Value.Equals(value));
    }

    #region GetFlagList

    /// <summary>
    /// Splits a bitwise-OR'd set of enums into a list.
    /// </summary>
    /// <param name="enumType">the enum type</param>
    /// <param name="value">the combined value</param>
    /// <returns>list of flag enums</returns>
    /// <remarks>
    /// from PseudoCode.EnumHelper
    /// </remarks>
    private static Enum[] GetFlagList(Type enumType, object value)
    {
      ulong longVal = Convert.ToUInt64(value);
      string[] enumNames = Enum.GetNames(enumType);
      Array enumValues = Enum.GetValues(enumType);

      List<Enum> enums = new List<Enum>(enumValues.Length);

      // check for empty
      if (longVal == 0L)
      {
        // Return the value of empty, or zero if none exists
        if (Convert.ToUInt64(enumValues.GetValue(0)) == 0L)
          enums.Add(enumValues.GetValue(0) as Enum);
        else
          enums.Add(null);
        return enums.ToArray();
      }

      for (int i = enumValues.Length - 1; i >= 0; i--)
      {
        ulong enumValue = Convert.ToUInt64(enumValues.GetValue(i));

        if ((i == 0) && (enumValue == 0L))
          continue;

        // matches a value in enumeration
        if ((longVal & enumValue) == enumValue)
        {
          // remove from val
          longVal -= enumValue;

          // add enum to list
          enums.Add(enumValues.GetValue(i) as Enum);
        }
      }

      if (longVal != 0x0L)
        enums.Add(Enum.ToObject(enumType, longVal) as Enum);

      return enums.ToArray();
    }

    #endregion GetFlagList

    #endregion Private Methods

    #region IDisposable Members

    void IDisposable.Dispose()
    {
      if (this.writer != null)
      {
        this.writer.Dispose();
      }
    }

    #endregion IDisposable Members
  }
}
